A crossed field or rotating plasma gun is investigated to determine detailed processes taking place during the ionization and acceleration phases. Measurements suggest that the gun breaks down via a spoke which subsequently rotates at the limiting velocity. Internal shorting occurs subsequent to break down and limits the usefulness of the source. Methods of reducing the effects of this shorting are presented as are some measurements of the properties of the plasma after it leaves the gun region. These suggest that about 1019particles can be accelerated to energies of several hundred eV.